The present invention relates to a device for measuring at least one parameter of a medium flowing in a line.
German Published Patent Application No. 196 52 153 describes a device having a measuring element for measuring a mass of a flowing medium, in which a flow straightener with a screen is provided upstream from the measuring element. The flow straightener with screen is installed in a rigid conduit inside the line, thereby constricting the line.
German Published Patent Application No. 197 38 337 and U.S. Pat. No. 5,892,146 respectively describe a hot-wire air-flow meter, having an orifice that forms a single unit with one wall of the line and is located upstream from the measuring element. This arrangement constricts the line and increases the flow velocity of a forward mass flow with pulsating flow downstream from, and within the diameter of, the orifice without destroying the flow.
Ring-shaped constrictions in devices, such as those described above may, under certain flow conditions, produce acoustic disturbances in the line that become noticeable in the form of whistling sounds.
These disturbances are triggered by ring-shaped eddies arising downstream behind one edge of the constriction and propagate in the direction of flow of the line.
German Published Patent Application No. 198 156 58 describes a device having a measuring element to measure a mass of a medium flowing in a line, with a flow pipe being located in the line and the measuring element being provided in the flow pipe. Any loud, disturbing whistling noises that occur are reduced by structural grooves in the end face of the flow pipe.
The device according to the present invention has the advantage that acoustic disturbances are avoided. This result is achieved in that suppression elements are used to reduce the formation of ring-shaped eddies.
At least one prevention element may be integrated into a rigid conduit of a flow straightener or into a second rigid conduit to simplify manufacturing.
If there is no flow straightener or rigid conduit, integrating at least one prevention element into one wall of a line may simplify manufacturing.
According to one arrangement of the suppression elements, the latter may be evenly distributed in the circumferential direction of the line and have the same shape to avoid distorting the velocity profile of the flow.
At least one suppression element may be configured as an elevation in the line to simplify manufacturing.
One example embodiment of the suppression element provides an orifice with different sections, the radial spacing of which varies in relation to a center line of the line.
The prevention elements may be rounded against the main direction of flow to avoid distorting the velocity profile of the flow.
A tubular body may be provided in the line, thereby avoiding a deviation in the measurement characteristic of a measuring element, caused by the impact of fluid or solid particles.
A protective screen may be integrated into the line or into the tubular body.